Air pollution and otitis media: a review of evidence from epidemiologic studies.

Otitis media (main types: acute otitis media and otitis media with effusion) is one of the most common childhood infections, particularly before the age of 3 years. The main causes are viral and/or bacterial ear infections, commonly accompanied by or following upper respiratory tract infection. Besides these infections, other risk factors, such as male sex, young age, genetic predisposition, low socioeconomic status, low vitamin A and C intake, and bottle-feeding are discussed. There is indication that exposure to environmental tobacco smoke is a major environmental risk factor, although additional effects of the exposure to ambient air pollutants is uncertain. Although some studies reported statistically significant increased risk for otitis media in children with high exposure to ambient air pollutants, the risks were not consistent among the studies. Owing to the scarcity of available data, far-reaching conclusions cannot be drawn yet. However, the evidence of an increased risk for environmental tobacco smoke exposure and identified increased risk for ambient air pollution exposure in some studies should stimulate future research using otitis media as one of the major outcomes in air pollution epidemiology.